The Orbit Where Some Satellites Go to Sleep

Sputnik 1 became the first satellite to enter orbit in October 1957. By January 1958, it was reentering Earth’s atmosphere and burning up. Nearly 60 years later, satellites have flown above Earth, the moon, sun, planets and beyond.

Some of the oldest satellites are still up there. Vanguard-1 was the first solar powered satellite when it launched in March 1958. Today, it’s still kicking around. You can keep tabs of its orbit over at the satellite tracking website N2YO. According to that website, there are 1,444 man-made objects crossing the visible sky above my house right now.

When the first satellites were launched, we weren’t thinking about the trash we were leaving up there. Decades later, it’s becoming an unavoidable problem. Defunct satellites, leftover rocket bodies, random space debris. There are thousands upon thousands of pieces of trash at various altitudes above Earth. The upper stage of the rocket used to place Vanguard-1 in orbit is still up there.

A new video from the European Space Agency puts a spotlight on the problem. I’ll embed it below, but I want to touch on one part of the video in particular.

The Graveyard Orbit

Getting rid of a satellite after its mission is done seems simple, right? Just deorbit the satellite and let Earth’s atmosphere chew it up. That works for satellites in low-Earth orbit, but not geostationary.

The geostationary ring, located 22,236 miles up, is one of the busiest places in space. It’s the one orbit where satellites move in tandem with Earth. A satellite placed here will always stay above the same location on Earth. Perfect for vital weather and telecom satellites. On average, two objects are only 190 kilometers apart here according to the ESA.

When a satellite becomes unresponsive here, it can endanger nearby satellites. Experts recommend satellite operators conduct a final maneuver to lift their aging satellites at least 300 kilometers higher. This new orbit is commonly dubbed a graveyard orbit. Here, satellites that did their time but can’t be deorbited float harmlessly above the important geostationary ring.

A shift in orbit isn’t enough, though. Older satellites can release debris and explosions are even a possibility due to residual energy sources. Think batteries, fuel and pressure tanks. Releasing this residual energy is “fundamental” according to the ESA.

An explosion in the graveyard orbit can send large chunks of debris back towards the geostationary ring or in lower orbits. That also increases the likelihood of a scenario called the Kessler syndrome (or effect). NASA scientist Donald J. Kessler proposed a dire scenario in 1978. One collision between objects cascades into more and more collisions. Worst case scenario would mean important orbits around Earth could become unusable.

Two satellites collided in orbit in 2009. A commercial Iridium communications satellite and a defunct Russian satellite flew into each other above northern Siberia. That collision created hundreds of new pieces of space debris, but thankfully, didn’t lead to a cascade of other collisions.

The new ESA film highlights the need for removing space debris. Space is only getting more crowded. Private companies like SpaceX, Blue Origin and others are pushing into the final frontier in a hurry. Satellites are even easier to design and place into orbit thanks to CubeSats.

Space agencies and aerospace companies need to come together to address this problem.

Cleaning up the debris is one solution. Another is a robotic refueling spacecraft. NASA is testing the technologies as part of the Rocket Refueling Mission. One day, a robotic spacecraft could reach aging satellites and perform repairs and refuel them. Besides making satellites last longer, it could give satellite operators more options in emergency situations or deorbit their satellites.

The final frontier is only going to get busier. We need a plan to make sure it stays that way.